The Department of Environmental Conservation says a supply pipe broke in one of Huron's buildings in January.
It leaked 10,000 gallons of a heating fluid. The DEC says the chemical is 60-percent water and 40-percent ethylene glycol, which is similar to antifreeze.
About half of it went into the storm sewer and into the Susquehanna River. The DEC says because it is mostly water, it dissipates quickly.
But Resident Action Group of Endicott, or RAGE, is still concerned about the impact on drinking water downriver.
"If this happened on the 18th of January, why wasn't the people of the community informed of this?" says Alan Turnbull of RAGE.
A spokesperson for the DEC says it responds to an average of 1,400 chemical spills in our region every year. It only notifies the public about those which pose a known danger health or the environment.
The DEC says it is taking tests from groundwater monitors, and should have results by the end of April.